Guide for correct grinding of twist drills



Aug. 1, 1933. w WARD 1,920,537

GUIDE FOR CORRECT GRINDING OF TWIST DRILLS F iled May 6, 1952 Fig. 2.

3nventor; MLF/EED 5 14 19/90:

(Ittorncg Patented Aug. 1, 1933 1 GUIDE FOR ooaaaor GRINDING or 'rwisr DRILLS 1 Wilfred H. Ward, Richmond, Ind, assignor to Robert H. Price, Richmond, Ind.

7 Application May 6, 1932. Serial No. 609,709

ZClaims. (01. 51-239 The object of my invention is to provide means which is located between the bearingsB and B, to enable an ordinary mechanic to properly grind and it provides means whereby the shaft may be twist drills, iii-order to obtain the results hereinrotated by power, however said shaft may be after set forth in the specification, driven otherwise than that suggested in the draw- 5 And another object is the provision of an atingtachment for employment with grinding twist Secured ona projecting portion of the shaft D is drills, which can be manufactured and sold at a the grind Wheel very low price, and employed with various styles Extending from the standard B is the flange 7 of grinding machines. or bracket G, to which is adjustably connected the 10 One way of carrying out the principles of my supporting mechanism, comprising the rigid head 5 invention, in a mechanically efiicient manner, H, a horizontal stein I slidable in the head H, and and that which in practice I have found to give adapted to be rigidly secured by the set-screw J. the best results, is shown in the accompanying Integral with the outer end of the stem I is the drawing, in which: Figure 1 shows an edge view,' head K. Slidably mounted in the head K is the or elevation, of my invention, in connection with vertical stein L, which is adjustably secured by 70 a drill grinding machine shown in elevation. Figthe set-screw M. Secured horizontally on the upure 2 shows a top plan view of my invention, taken per end of the stern L is the oblong work supportat rightangles to that of Fig. 1, showing a pering t ble N, which extends across near the face of tion of the table on which my device is mounted, the grinding wheel F, and it is parallel thereand showing a portion of a grinding wheel assowith. g 75 ciated therewith. Figure 3 is substantially the Letter P designates the working end portion same as Fig. 2,.except that it is taken on a larger of an ordinary twist drill, to the proper grinding scale; and shows a twist drill in one position, to be of which my invention is importantly contribuground, and showing, in dotted line, the drill in tory,and in fact absolutelynecessary.

position to be tested for accuracy in the work bei The drill shown herein has two spiral chan- 80 ing performed thereon. Figure 4 is an isometrinels, 7' and f, formed in the sides thereof and excal view of my invention alone. Figureb-is the tending therearound parallel .with each other. same as Fig. 4,-except that the position of the de- The working end of the drill has two'faces, f and vice is reversed. Figure 6 shows the working end J' formed thereon, each at an angle with relaportion of a twist drill. Figure '7 is the same as tion to the body of the drill, and at an angle with 5 Fig. 6, except that the drill is shown as having relation to each other, the juncture of the two been given a quarter turn. 'And Figure 8 is an faces, at the axial center of the drill, forms the end plan View of the drill. For abetter undercutting blade which terminates at the points of standing of the size of the parts with relation to the drill, that is its center is the axial center of the each other, we will assume that Fig. 3 is full size; working end of the drill. Fig. 2 being half size; Fig. 1, being one-fourth The invention proper comprises an'oblong plate size; Figs. 4 and 5 being half size; and Figs. 6, '7 ,1, adapted to contact. flat on the table N, with it and 8 being full size. However said sizes are only straight edge, which extends from end to end relative, as the device may be of any size desired, thereof, adapted to extend flush and parallel with 40 and various size bits or drills may be operated the inner edge of the table N, as shown in Fig. 3.

upon without changing the size of the invention Formed in the right-hand end portion of the plate proper. 1, and parallel therewith, is a slot 2 adapted to In the drawing similar indices designate like receive the stern of v the bolt 3, which bolt has a parts throughout the several views, the parts head on its lower end and contacting with the which are old being designated by letters of refunderside of the table N, and on the upper portion erence, and those which are parts of my invention of said bolt is'threaded the winged nut 5 whereby being designated by numerals. The associated the plate 1 may be clamped tightly onto the table parts, with which my invention may be employed, N, as shown in Figs. 1, 2 and 3.

comprises the pedestal A, which should be rigidly I Formed integral with plate 1, and extending secured in the position shown inFig. 1. Extendupwardly therefrom, are the two angular and ing upwardly from the head of thepedestal are upwardly tapering ridges '7 and 8, the outer sides the spaced apart standards B and 13, carrying of which are at right-angles to the plate 1, while the respective, spaced apart, bearingsC and C, their inner faces are angular, converging in the which carry the shaft D revolvably mounted center at the line 9. Said line, or point of contherein. Secured on said shaft is the pulley E, vergence of the inner faces of the members '7 and '110 8, extends upwardly and forwardly at an angle from near the bottom of the outer edge of the plate 1 to near the forward terminals of the ridges 7 and 8, thereby providing a V-shaped upwardly and inwardly extending channel, as shown most clearly in Figs. 2 and 5. The outer left-hand corner portion of the plate 1 is formed angular; to provide the angular edge 6, which is at right angles to line 9.

Integral with the surface of the plate 1, adjoining the member 8, and located adjoining the outer edge of said plate, is the. lug 10, whose free-end forms an angular shoulder 11, which extends even with the underside of the plate 1, which will hereinafter be further explained.

Integral with the surface of the plate 1, and extending parallel with and adjoining the outer edge thereof, is the graduated scale-bar 12, one end of which adjoins the lug l0, and the shoulder 11. Said scale bar is for the purpose of determining the diiferences if any, between the radial length of the faces ,i and f of the working end of the drill,'in order that the same may be corrected by the application of the faces of the drill to the grinding wheel F. Said scale acts as a determinative element as follows: Suppose, for instance, that the .drill be placed in the position in which it is shown in dotted lines in Fig. 3, the angle of the shoulder 11, with relation to the edge of the scale bar 12, is such that the blade f, being then in-vertical position, will be brought to a definite point of the scale, thereby determining the length of the face f which position will be noted by the operator. Then by giving the drill a half turn in an axial direction, the other face f will be brought to the same position as was the face ,f thereby enabling the operator to compare the difference, if any, and then by contacting the longer face of the drill to the wheel F be is able to make them equal, thereby correctly centering the drill.

It is to be observed that my complete guide shown in Figs. 4 and 5, is formed by a single piece of material, that is to say,-all of the parts are integral with each other. r

The operation of my invention is extremely simple, after one has mastered his own movements with relation thereto. The operations which have been suggested above, may be carried out as follows: Resting the forward portion of the drill in the notch which is formed by the members 7 and 8 and parallel with the junction line 9, one is given the proper angle to form the faces 1 and f, at the same time rotating the drill axially,

while the rear or stem portion of the drill is moved up and down, thus one is enabled to give the face face is held in contact with the revolving grinding wheel, the operator should impart to the drill limited gyratory movements, combined with substantially Vertical movements of the stem of the drill, but without lifting the working end portion of the drill from contact with the guide, whereby While the face of the drill will be formed diagonally in a straight line from point to periphery of the drill, yet the face of the drill will be formed rounded in an axial direction, with all the parts thereof concentric with the axis of the drill stem.

All of the operations required for properly grinding a drill are accomplished without removing the drill from contact with the members '7 and 8, by which the drill is always properly supported for accurate grinding thereof. Only the determining of the relative width of the faces I and f to each other, requires the removal of the drill from the notch formed by the members 7 and 8', and this of course is not a grinding operation.

It should be noticed that the V-shaped channel formed by the members 7 and 8 may, if desired, be formed U-shaped, or as a half circle.

I desire that it be understood that various other changes may be made in the several details herein set forth, and the arrangement and relative sizes of the parts thereof, without departing from the spirit of the invention or sacrificing any of the advantages thereof which are new and useful,

and which involve invention.

Having now fully shown and described my invention, what I claim, and desire to secure by Letters Patent, is-- 1. A guide for the correct grinding of twist drills, comprising an oblong plate, means for securing said plate in operative position with relation to a grinding wheel, a pair of ridges integral with said plate and extending thereabove, said ridges being located diagonally with relation to said plate and with each other and providing a Vshaped channel between said ridges, with said channels formed tapering convergently with the juncture of said ridges inclined at an angle with relation to said plate.

2. A device for facilitating the correct grinding of tools, comprising a single unit adapted to be detachably secured in horizontal position in front of a grinding wheel, and consisting of a plate, a pair of ridges projecting upwardly from said plate and extending th'ereacross at different angles with relation to each other and with relation to said plate, with their forward ends approaching near to each other and diverging apart to their rear ends, with a V -shaped channel formed between said ridges, the center line of said channel being at an angle sloping upwardly from the rear edge to the forward edge thereof, and means carried by said plate for determining the accuracy of the grinding operation at the will of the operator, all substantially as set forth.

WILFRED B. WARD. 

